1. Field of the Invention
The present invention relates to a repairing apparatus for a damage internal wall (refractory lining) of an industrial furnace such as coke ovens and refinery furnaces.
2. Prior Art
The internal wall of an industrial furnace such as coke ovens and refinery furnace is constituted by lining a refractory material such as firebrick thereon. However, the internal wall of the industrial furnace is repeatedly exposed to high temperatures of 1,000.degree. C. or more, so that not only it is thermally damaged by high temperature substances but also the damages such as cracks and separation are produced on it by the repeated expansion and contraction. Therefore, the effective repair of the above described thermal damage, crack, separation and the like of the internal wall of a furnace under a safe environment is an important problem in the operation of an iron works having such industrial furnaces.
The repair of the internal wall of the above described industrial furnace has been carried out by a wet repairing process in which a repairing material, which is a formless refractory material prepared by mixing binders, is sprayed onto damaged parts by means of a spraying apparatus inserted into the furnace through a furnace inlet or a spraying apparatus brought into the furnace by an operator once stopping the operation of the furnace. However, in this wet process, in order to give the repairing material a sprayable condition, binders which contain water are mixed to give high viscosity. Accordingly, when the repairing material sprayed onto the damaged parts is heated after application, water contained in the binders is explosively evaporated according to circumstances thereby the repaired parts are separated. Also, when the binders are insufficiently blended with the repairing material and the binders are not uniformly distributed, the adherence of the repairing material to the furnace wall is not uniform. In addition, the problem has occurred in that only the parts adjacent to the furnace inlet can be repaired and the like.
A dry repairing process, in which metallic or semi-metallic minute particles as repairing material are thermally flame sprayed or sprayed along with an oxidizing gas and the metallic or semi-mettalic repairing material is sintered by heat generated at that time, has been known for a process of solving the problem incidental to such wet repairing process. In comparison with the wet process, this dry repairing process has the advantages in that the binder is not required whereby having no effect by water contained in the binder. Furthermore, a flame or a gas stream used for spraying is diffused, so that the dry repairing process is suitable for adhering a large amount of repairing material to a wide range. However, in the case that it is necessary to repair narrow damages such as cracks and those in a joint portion of firebrick with high accuracy, the repairing material is adhered also to the surroundings of the damaged parts to form projections within the furnace wall. Under such condition, in coke ovens, a hindrance is occurred in the pushing-out of coke, so that the dry repairing process is unsuitable for the operation of the furnace. Also, in the same manner as in the above described wet repairing process, the problem that only the portion adjacent to the furnace inlet can be repaired can not be solved.
In view of the above described circumstances, the present inventors disclosed a repairing process of an internal wall of a furnace utilizing the plasma spraying in Japanese Patent Application Laid-Open No. 58-49889 (1983).
This invention consists in that an operation gas which is added N.sub.2 as to Ar gas generates a plasma jet and the powders of refractory materials such as ceramics as a repairing material are thermally sprayed onto a furnace wall with heating the furnace wall by the resulting plasma jet. Since this invention relates to a dry repairing process in which the powders of refractory materials such as ceramics are used for the repairing material, the disadvantages, such as an explosive evaporation of water, incidental to the wet repairing process can be eliminated. Also, since a flame of plasma jet can be made narrow, this process is suitable for the case where it is necessary to spray the repairing material with high accuracy onto only the narrow damaged parts such as cracks. In addition, this process has advantages in that the repairing material shows a strength nearly equal to that of a brick upon its thermal spraying; the bond strength between a brick constituting the furnace wall and the repairing material is great since they are welded to each other; the repairing material is compact and impermeable to a gas such as water vapour and CO gas after welding; there is little influence upon the furnace wall since the welded part of repairing material is not rapidly chilled; the degree of freedom of the selection and combination of repairing materials is comparatively large; and the like.
However, if the repair of an internal wall of furnace can be carried out without lowering a temperature of the furnace so much, ideally at usual operating temperatures, it is remarkably advantageous in respect of operational efficiency, energy efficiency and the like. On this account, the repair has been carried out by means of a spraying apparatus or a spray gun brought into the furnace by an operator once stopping the operation of the furnace but it has been desired to realize the remote controlled-repairing operation in view of safety, improvement in working circumstance and possibility of carrying out the repair in the depth of the furnace.
In view of these circumstances, in order to remote control a spray gun and the like, for example Japanese Patent Application Laid-Open No. 53-82802, Japanese Patent Publication No. 57-48611 and the like in which the position of a spray gun is controlled by the visual observation and Japanese Utility Model Publication No. 57-46360 and the like, in which the outline of the positional relation between a damaged part of a furnace wall and a spray gun is read by one image pickup apparatus inserted into a furnace to control the position of the spray gun, have been proposed. However, since an object to be controlled is a usual spray gun in these inventions and utility models, the control need not be high in accuracy, so that their application to the plasma spraying, in which a repairing material can be thermally sprayed with high accuracy, is not effective practically.
So, the present inventors disclosed also a method of controlling the position of a spray gun and the like three-dimensionally using two television cameras and a laser spot ray-radiating apparatus in abovementioned Japanese Patent Application Laid-Open No. 58-49889. However, also in this method, an art for remote controlling a spray gun with high accuracy is required from angles that the value based on the result obtained from the experiments, which were preliminarily carried out, is used as the optimum distance between the spray gun and the furnace wall; in the case of plasma spraying, the distance between the spray gun and the furnace wall have a great influence upon the adhesion efficiency of a repairing material such as ceramics; the advantage of being capable of repairing narrow parts of a furnace wall such as cracks with high accuracy can be effectively utilized by using the plasma spraying; and the like.